Wire controlled snap switch



P 4, 1956 J. SCHMIDINGER 2,761,931

WIRE CONTROLLED SNAP SWITCH Filed April '7, 1953 2 Sheets-Sheet 1 TILEJ...

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2 Sheets-Sheet 2 Filed April 7, 1955 r1 1 I. rm I lm/I I I 56 60 70 INVENTOR. 1/0552 Sam/away? BY hfw 6 mm ATTOPMFYS b Q N O Patented Sept. 4, 1956 short wires. This feature also aids to a considerable extent, the natural and unfailing transformation of the described single bow into the characteristic double bow or 2,761,931 generally M shape of the strip. The generally longitudinal disposition of the pull wire is also advantageous from WIRE CONTROLLED SNAP SWITCH a constructural point of view as it allows extremely com- Joseph Schmidingen Lake George, N. Y. I pact deslgn' The slots defining the central strip of the snap plate may be parallel but preferably they are angularly disposed to define a strip decreasing in width from a maximum adjacent the fixed end of the plate. This construction permits the introduction of a relatively strong bias at the wide end of the strip and of a relatively weaker bias, which is desirable, at the narrow end of the strip, while The p mvenhoh relates to expahslble Wlm 1:) insuring that the unbiased portion of the strip is relatively trolled snap switches, more particularly to the class li h d i 1d b1 Application April 7, 1953, Serial No. 347,380

. '12 Claims. (Cl. 200-113) wherein an expansible w e moves e free en of a p Change in tension of the pull wire for operation of the member ILO different circuit controlling pos1t1ons with a i h occurs as a result f passage f current theresnap action, and C mPI a 0 f this yp 00 through, as in conventional pull wire switches. The new liif ggli 2 3:12 gllzl fgp l igpg igg g siwitchdmay be designed for series or shunt operation as e O 1 O 1 a 101']. no esire Switch y he Opemted as a flasher, a relay, a Tlme F For a better understanding of the invention and of an ovelload p l g Q Valliige legulatol, depending switches embodying the same reference may be had to upon e associate circui connections. he accompanying d i f hi h;

There are two types of wire controlled switches now in Fi 1 1 l i f preferred f rm of snap plate Wide commercial use, particularly in the automobile inf use i a Snap it h b dyi g th invention; dustry. These are the electromagnetic type, exemplified Fi 2 i a id i f th 5113p plate f Fig, 1; by the SVltCllES described and claimed in Schmidinger Fig 3 is a iew similar {9 2 bu sh v jng thg pun Patents and 2 ,v and the vane one wire secured to the central vane of the snap plate. exemplified by the switches disclosed" and claimed in Fig 4 i a series f id view of a snap plate of a h g P8i611ES'N0S-L074i345,2;l33,309,2,256,499, switch and explanatory of the method of adjustment, 2, 99,767; a o h h electromagnetic yp the views A, B and 0 thereof showing the change in conllifi i0 Current and vhltagfi' fluctuations- Vaile YPfi formation of the central strip of the snap plate during is limited in current capacity. Also, there re a n m er increase in the tension of the pull wire to that desired for of prior art wire controlled snap action switches of the optimum operation of the switch; class described but all of these consume an excessive Fig. 5 is a series of two side .views of the snap plate amount of power (wattage) for their operation directly of an adjusted switch connected in a circuit and explanadue to their design. The switch of the present invention .tory of the operation of the switch as a flasher;

can be made insensitive to current and voltage iiuctua- Figs. 6 and 7 are side and front views, respectively, of tions, will operate over a wide range of current values a snap switch representing one embodiment of the invenand develops positive and firm contact pressure with extion;

tremely low wattage consumption for its operation: Fig. 8 is a longitudinal view, partly in elevation, of a The new switch comprises essentially a metal plate switch representing another embodiment of the invenrnember adapted to be mounted at one end and carrying tion;

one or more contacts at its free end, the plate being pro- 5' Fig. 9 is a longitudinal view partly in elevation of a vided with two generally longitudinal slots which terswitch differing only slightly from the switch of Fig. 8 and minate short of the ends of the plate and define a central illustratirlilg the relllatigellgy msignpr changes required for 1clonstrip. The central strip is biased or sprung at both ends Vetting t e switc 0 i2- Tom Sefles yp SWltC i0 and a pull wire, which is secured to the strongly. biased a. Shunt type switch; and

section of the strip adjacent the fixed end of the plate, Fig. 10 is a perspective view of one of the elements extends substantially parallel to the plate. The bias oi oi the Switch 0f fillhel' Fig 3 the two ends of the strip is such that the strip assumes a F Thelinvergtion 1will first lbhe desgribed with ({eference to natural single bow shape before the wire is tensioned. 10 inc uslveguffis am l'l'ecied P When the wire is tensioned, the strip assumes the form marlly'to the i l Plate 0f f Switch but fe at of a generally M-shaped curve-with theinitially unstressed Y leiist diagrammatically, sul'hcleht 0f lhfi P assoclilled intermediate portion of the strip forming the depression With the Plate make clear the construction, l h

of the M. During operationtof the switch, the radii of ment: Operation of the P The snap Plate, m

the preferred embodiment illustrated in Fig. 1, comprises .a rectangular plate 2 having rounded corners and provided with two slots 4-4 which extend for the major length .of the plate. The slots 4, 4 define a central strip 6 which tapers in Width from one end to the other and this strip 6 during manufacture or mounting of the plate, is so stressed or otherwise placed under tension its ends as to cause the strip to bow outwardly from the curvatures of the parts of the strip vary in magnitude but not in sign. Fixed contacts or stops are positioned on o opposite side of the free end of the plate for engagement therewith, the free end snapping from one contact or stop to the other. with change in tension in the wire.

An important feature ofthe above briefly described switch is the combination of the biased strip with the tensioned wire exerting a. generally longitudinal pull on plane of the plate as illustrated in Fig. 2. The and of the strongly biased part of the strip. This feature insures the plate adjacent the Wider end of the vane 6 is Welded that all the motive Power Supplied by the expanding and or otherwise secured to a fixed fiat frame element 8 of Contracting Wlfe is trahsmllted to and utilized by the the switch and the other, or free, end of the plate cardescrlbed central Portion of the P for Causing the ries acontact member 10. An L-shaped anchor member free end of the plate to snap from one position to another 12 of round stock has one leg welded to the convex side an is one reason y it is possible to p y relatively of the strip 6 adjacent the fixed end of the plate. Preferably the sections of the plate on opposite sides of the wider end of the strip are given a slight crimp or bend tending to cause the free end of the plate to be lifted slightly above the plane of the frame element 8. This lifting bias of the plate may be introduced when forming the plate or may be effected by a slight bending after mounting or it can be effected by frame projections .or by location of the stops with which the plate cooperates as hereinafter described. in FifS. I through this lifting bias has been indicated on an exaggerated scale as a fold or ridge 14 but the resulting angular disposition of the plate with reference to the plane of the surface of frame element 3 has not been indicated in the drawing as the angle is so small as to be unnoticeable to the eye.

Associated with the snap plate 2 and frame element 8 are fixed, preferably adjustable, steps or contacts 16 and ill which are disposed in spaced relation at opposite sides of the contact 10, stop 16 being positioned to engage contact when the central strip 6 of the plate is in the bowed shape illustrated in Figs. 2 and 3. Also associated with the parts so far described is an adjustable (or bendable) bracket 20 and a pull wire 22 which extends generally parallel to the plane of the plate from the upright leg of anchor member 12 to bracket 20, the Wire being firmly attached to both anchor member 12 and bracket 26. In the particular embodiment illustrated in Figs. 3 through 5 the pull wire 22 is secured to the bracket 20 by means of a bead 24 of glass or the like which is fused about the wire and supported in an eyelet formed in the bracket.

After mounting of the snap plate 2 on the frame element and attachment of the pull wire 22 to the anchor member 12 and bracket 20, the switch is adjusted by bending or moving the bracket 20 to increase the tension in the pull wire. The effect of such increase in tension is illustrated in Fig. 4. Fig. 4A represents the initial effect of introduction of tension into the. pull wire 22 by slight pivotal movement of bracket 20 about its lower end 20a. The longitudinal pull on the strip causes the intermediate initially unstressed or neutral portion 6a. of the strip to go into concavity, while the end sections of the strip remain in convexity due to the initial. bias therein. In this position pressure begins to build up between contact 10 and stop 16.v When the bracket. 20 is moved to the position indicated in Fig. .4.-B,. thetension in the pull Wire is suificient to cause the portion 6a of the stri to pass beyond the plane of the plate, the strip rsthe contour a relatively flat. M. Further increase in tension in the pull ment of the bracket 20 to the position shown in Fig. 4-0 forces the central part 6a through. aposition of unstable equilibrium at which instant some of the compres sive forces accumulated in the strip by the longitudinal pull of the wire is released and operates, to snap the free end of the plztc with the contact i=3 away from stop 16 and into engagement with stop 18. The switch is now in adjustment.

Operation of the switch is efiected by expansionv and contraction of the wire to change. the. tension therein. For this purpose, as shown in view A of Fig. 5, a ballast resistance 26 may be inserted between wire 22 and stop or contact 16, which contact may be connected to a terminal, indicated at L, to which lamps to be flashed may be connected. With this arrangement, when positive potential is applied to frame element 8 as indicated by the sign, and the switch is in the adjusted position of Fig. 4-C, current will flow from the frame. element. 8 through the plate and strip thereof to. anchor piece 12, wire 22, resistor 26 to terminal L and through lamps connected therewith. This current, while insufficient to cause the lamps to glow, will heat the wire 22 causing it to expand and releasing the tension therein. The two biased sections of the strip will then move the concave section Go upwardly toward the plane of the plate'while wire 22 by movecontact 10 is engaging and building up pressure against stop 18. Upon further expansion this section 6a is forced through the critical line of plate 2 by the combined forces of the end biases of the strip and the straightening tendency of the central concavity at which instant accumulated compressive force is released and operates to snap the plate contact 10 away from stop 18 and into firm engagement with stop 16 into the position shown in Fig. 5-B. At this instant the pull wire 22 and ballast resistor 26 are shunted, by the plate 2, the lamps are lighted and the pull wire starts to cool and contract to repeat the cycle and flash the lamps. If, as indicated in Fig. 5-B, stop 18 is an electrical contact and if a lamp is connected thereto alternate flashing of the lamps connected to contact 16 and terminal L will result as the plate snaps from the position of Fig. 5-A to that of Fig. 5-B.

By constructing and assembling the device in the manner described above, it has been found that the central strip is always in complete functional control over extremely wide speed ranges and allows the splitting of the on and off periods in infinite degrees. The chief reason for this unusual control is that the biased and sections of the strip always remain in convexity, while central section 6a always remains in concavity and therefore only the amplitudes of the respective curvatures are changed during the operation of the device. Since no reversal of any of the three curvatures occurs, the mere changing of amplitudes can be caused by very slight expansion of the pull wire which can therefore be very short per given power (wattage) used to expand it and relatively thin since it will never be subjected to the harsh shocks which are characteristic with reverse buckling members. These statements are supported by successful tests with pull wires of one inch in length and of .002 inch in diameter and also by tests with a flasher made in the manner described which flashed at cycles per minute a milliampere lamp connected in series with a pull wire only 1 1 long the device operating at a terminal drop of only 0.1 volt.

It should be noted that the closely spaced parallel arrangement of the two longest parts, the pull-wire 22 and the plate 2 not only allows extremely compact unit dcsign, but contributes to a large degree to the functional efiiciency of the device since the horizontal motion of the wire 22 is converted by the short pull piece 12 into perpendicular motion of the vital section 6:: of the strip 6. Since the pull piece 12 is much shorter than the distance between the point of its attachment to the vane and the section 6a, motion amplifying leverage is effected so that the slight movement of piece 12 results in relatively large movement of section 6a. The changing of the amplitudes of the three curvatures previously described is greatly smoothed by this system of conversion of horizontal into perpendicular motion and is one of the reasons why this device will function elficiently with much lighter tensible loading of the pull-wire than would be possible for example if the vane would be pulled or pushed perpendicularly relative to its plane.

As the bias introduced into the strip at the end adjacent the mounted end of the plate is stronger than that introduced into the other end the amplitudes of the convex portions of the strip after adjustment will not be equal nor will the concave portion necessarily occur at the exact center of the strip. The drawings, in this respect, may be considered diagrammatic, with curvatures of the-strip exaggerated for better understanding of the operation and with no attempt to illustrate exact dimensions.

One constructional embodiment of a completed switch incorporating the snap plate and associated part heretofore described is shown in Figs. 6 and 7 to which reference may now be had. The switch shown in these figures is mounted on an insulating disk 28 of Bakelite af sai orthe like to the under surface of which are secured three terminal connectors30, 32 and 34 and about the periphery of which a suitable cover member, not shown, for the switch element could be crimped in conventional manner. A frame member 36 formed from sheet metal stock is mounted on the upper surface of the disk 28 by means of a rivet- 38 which also serves to secure terminal connector 32 to the disk, the rivet electrically connectingthe frame and terminal and passing through the lower part of the frame 36a which is bent back from the plane of the major part of the frame to serve as a support leg therefor. A strip or tongue 36b is bent forwardly from the upper part of the leg 36a to serve as the adjustable anchoring means for the pull wire 22, the tongue 36b being spaced above the disk 28 to allow for adjustment of the end thereof in a vertical direction. The upper end 360 of frame 36 is bent forwardly and then upwardly to provide a fiat vertical surface 40 for attachment thereto of the snap plate 2 which extends downwardly parallel to the main part of the frame and spaced therefrom by the part 360 of the frame. The fixed contacts 16 and 18 of the switchare mounted on upwardly extending fingers 42 and 44 respectively formed in metal plate members 46 and 48 respectively. These plate members, interleaved with suitable insulating plates of mica or the like, are disposed parallel to the main body of the frame 36 and held firmly thereagainst by a pair of wing sections 36d of, the frame which are clamped by a suitable die press about the plate members 46 and 48 and insulating sheets after assembly. Plate member 46 at its lower end has a leg portion 46a which is bent forwardly and downwardly to serve as an electrical conductor, the leg being secured to the disk 28 by a rivet 50 which serves also to secure the terminal connector 30 to the disk. Similarly a leg 48a of plate member 48 is bent forwardly and downwardly and secured by a rivet 52 to the disk, the rivet serving also to secure terminal connector 34 to the disk. In order to permit adjustment of the spacing of contacts 16 and 18,. the

fingers 42 and '44 are each provided with an apertured I tab, 42a and 44a respectively, by means of which a lateral bending pull or push can be exerted upon the associated finger, frame 36 being provided with an aperture alined with tab 42a for access thereto. The pull wire 22, which is secured at its upper end to anchor member 12 and fixed by the insulating head 24 in an aperture in tongue 36b, is secured at its lower end to rivet 50, the portion of the wire between bead 24 and rivet 50 serving as the ballast resistor 26 of the switch.

The operation of this switch of Figs. 6 and 7, being identical with that described with reference to the diagrams of Fig. 5 needs no further description. With no tension in pull wire 22 contact 16 is adjusted by tab 42a to a position where the contact is touching, but not pressing upon, the plate carried contact 10. Contact 18 is then adjusted by tab 44a until the spacing between the fixed contacts is that desired in accordance with the particular requirements of timing of the switch, the closer the spacing the more rapid the rate of flashing. The tension in pull wire 22 is then increased by bending of tongue 36b downwardly until the plate snaps into the position illustrated in Fig. 6, that is, with contact engaging contact 18 under pressure.

The above described construction of switch requires a total of only 19 parts which can be reduced to 16 by substitution of clinch-type terminals for theriveted terminals illustrated. The construction readily lends itself to mass production methods.- The contact carrying plate members are of identical construction, requiring a single die and these plates, the insulator spacer sheets and the plate which after bending forms the frame, can be provided with alining holes for mounting on alining pins during the shaping and clamping operations ina die press. The frame, being of metal, readily dissipates heat generated during the operation of the switch.

, still simpler construction of switch is disclosed in Figs. 8 and 9, Fig. 8 representing aseries typeswitch and Fig. 9 a shunt type of substantially identical construction. The construction common to both Fig. 8 and Fig. 9 will first be described. An elongated frame member 54 formed of U-section metal stock has its side walls turned inwardly to clamp therewithin-two flat conductors 56 and 58 which are insulated from the walls of the frame 54 by a sheet 60 of insulating material folded aroundlthe conductors during the clamping operation. Conductor 56 extends from beyond one end of the frame 54 to about the central portion thereof where it terminates in a raised shoulder 56a and a tail portion 56b generally perpendicular to the frame 54 and protruding out therefrom through the space between the turned in side walls. The shoulder portion 56a is disposed within an opening 54a in the upper wall of frame 54 and serves as one of the adjustable stop members of the switch. Conductor 58 extends from the neighborhood of the opening 54a to and beyond the other end of frame 54, the conductor being turned upwardly beyond the end of the frame to provide an adjustable arm 58a for anchorage of the pull wire 22. Preferably, for ready bending of the arm during adjustment of wire tension, the arm is weakened by, removal of metal as indicated at 58b. In the case of the series type switch of Fig. 8 the metal is removed from arm 58a but not from the body of the conductor 58 and hence serves as a terminal 580 of the switch. The snap plate 2 is mounted on a step 62, corresponding to frame element 8 of Figs. 1 to 5, which is a projection of the upper wall of frame 54, at the end thereof remote from arm 58a. The free end of the plate 2 is disposed over the stop 56a and beneath an overhanging arm 64a of a generally hook-shaped member 64 serving as the other adjustable stop of the switch. Member 64 has a shank portion 641) which extends through the opening 54a in the frame and is welded to the tail portion 56b of conductor 56, permitting conjoint adjustment of the position of the stop members. Preferably, as shown in the detail view Fig. 10 of member 64, the member is weakened at the bend between the arm 64a and the upper inclined part of the shank portion 64b to permit adjustment of the spacing between the stop members. Both stop 56a and stop 64a may carry electrical contacts as indicated in Figs. 8 and 9.

When the above described construction of switch is to be used as a series switch, the under side of the free end of snap plate 2 is provided with an insulating button 66, as shown in Fig. 8 and the upper side of the free end is provided with an electrical contact for engagement with the contact carried by stop arm 64a. Conductor 56 is connected to a source of positive potential and part 580 of conductor 58 is connected to the lamp or lamps to be flashed. Thus, with the parts in the position illustrated in Fig. 8 and the circuit to the switch closed, current will flow from the source through conductor 58, hook member 64, the mating contacts carried by stop 64a and plate 2, through plate 2, wire 22, arm 58a to conductor 58 and lamp to ground. Upon expansion of wire 22. due to current therethrough, the free end of the plate 2 will snap down into engagement with the contact carried by stop 56a but due to the insulating button 66 the circuit will be open at this point. Thus the pull wire will cool to repeat the cycle and flash the lamp load.

If the switch is to be used as a shunt type switch, an insulating button 68 is provided on the upper surface of the free end of the snap plate 2 and a contact mounted on the under side thereof as shown in Fig. 9. A ballast resistor 26, which may comprise an additional length of the pull wire 22 is connected between arm 58a and the shank 64b of member 64. The lamp load is connected to the frame 54 and conductor 56 is connected to a source of positive potential; When the external circuit is closed, current will flow, from the source to conductor 56, shank 64b of member 64, resistor 26, wire 22, plate 2 and frame 54 to the lamp load, thus placing the ballast resistor in series with the lamp. The current through the pull wire causes heating and expansion and snapping of the plate 2 to contact closing position, in which position the resistor 26 and wire 22 are shunted from the circuit, the current now flowing from conductor 56 through the mating contacts to plate 2 and the frame and thence to the lamp load.

From the foregoing description of Figs. 8 and 9 it will be apparent that only minor changes are required for converting a series switch to a shunt switch when the specific construction illustrated is employed. Moreover. the illustrated construction is extremely simple and, like that of the switch of Figs. 6 and 7, lends itself to mass production methods. The frame and fiat conductors, together with the insulating sheet can be quickly and accurately nested and clamped by use of registering pins and alinement holes in the parts. Alinemeut holes for this purpose are indicated at 70 and '72 in the drawings.

Another advantage from a practical standpoint of the constructional features of the switch of Fig. 8 or Fig. 9 is that the frame and parts associated therewith, exclusive of the snap plate, is sufiiciently close to that now in wide commercial use in a vane type switch as to permit conversion to the new switch without major changes in manufacturing methods or apparatus. To illustrate this point the spacing between the fixed contact and the ends of the frame 54 in the embodiment of Figs. 8 and 9 has been made substantially the same as in the above mentioned vane type switch. This results in a switch having a pull wire which is much longer, with relation to the length of snap plate than is needed in the new device. The length of frame 54 between the fixed contact and arm 580 could be reduced at least to about half of that illustrated and still provide adequate length of wire for operation of the switch.

The invention has now been described with reference to the important features of the snap plate and of its operation and with reference to specific switch construction. in all of the figures of the drawings the parts have been shown in a scale greatly exaggerated from actual size for purpose of clarity. Although only the preferred form of snap plate has been illustrated, obviously the invention is not limited to the exact shape or construction thereof illustrated in the drawing. For example, the snap plate has been shown and described as comprising an integral metal sheet with the central strip thereof formed by slitting the plate and stressing or deforming the ends of the part defined by the slits. if desired the snap plate could be built up from a number of separate parts in which case the bias at the ends of the central strip could be introduced during the mounting operation, as by mounting of the ends on surfaces inclined to the parts upon which the side parts of the plate are mounted. Also, although the central strip has been shown as having straight tapering sides, the sides could be curved to reduce the width of the initially unstressed portion of the strip, in which case the increased width of the strip adjacent the free end of the plate would itself provide the bias at that end of the strip. Other configurations, such as central strips with straight parallel sides, or plates with non-parallel converging sides, are within the scope of the invention. The specific construction illustrated in Fig. l is, however, preferred as heretofore indicated. Such shape insures good operation and has a minimum electrical resistance, which latter feature is of particular importance in switches employed for flashing lamps. The snap plate and associated parts however specifically constructed, should so cooperate that durlng the operation the pull wire, through the angle pull piece, continually causes the unbiased section of the strip to move from one stable position through a line or point of instability to another stable position without reversal of curvature in any part of the strip.

The following is claimed:

I. In a wire controlled snap switch, a snap plate of electrical' conducting material comprising three strips interconnected at their ends, the outer strips being coplanar and the inner strip bowing outwardly from the plane of the outer strips, means for mounting one end of said plate, stop means positioned at opposite sides of the free end of the plate, an angle pull piece secured to said inner strip on the convex side thereof adjacent the fixed end of said plate and an expansible wire secured to said angle piece and extending generally parallel to said plate to a location beyond the free end thereof, means at such location anchoring said wire under sufiicient longitudinal tension to cause an intermediate section of the inner strip to curve oppositely to the ends thereof with the free end of said piate in engagement with either of said stop means, change in tension in said wire under contraction and expansion causing the free end of said plate to move from one stop means to the other with a snap action without reversal of curvature of the intermediate portion of said central strip.

2. The combination according to claim 1 wherein said snap plate is a metal sheet having longitudinal slots therein defining the inner and outer strips, the ends of the inner strip being deformed to how the inner strip outwardly from the plane of the plate.

3. In a wire controlled snap switch, a snap plate of electrical conducting material comprising three strips interconnected at their ends, the outer strips being coplanar and the inner strip bowing outwardly from the plane of the outer strips, means for mounting one end of said plate, stop means positioned at opposite sides of the free end of the plate, an angle pull piece secured to said inner strip on the convex side thereof adjacent the fixed end of said plate and an expansible wire secured to said angle piece and extending generally parallel to said plate to a location beyond the free end thereof, means at such location anchoring said wire under sufiicient longitudinal tension to cause an intermediate section of the inner strip to curve oppositely to the ends thereof with the free end of said plate in engagement with either of said stop means, said inner strip decreasing in width from the end adjacent the mounted end of said plate to the end adjacent the free end of the plate.

4. In a snap action switch, the combination comprising a metal plate fixedly mounted at one end and provided with a pair of slots defining a central vane, said vane curving outwardly from the plane of the plate, stop means positioned at opposite sides of the free end of said plate, an anchor member secured to the convex side of the end of said vane adjacent the fixed end of the plate, and a tensioned pull wire secured at one end to said anchor member and extending generally parallel to said plate toward the free end thereof, means tensioning in said wire sufficiently to cause an intermediate part of the vane to curve oppositely from the ends thereof, whereby during operation of the switch when the free end of the plate moves out of engagement with one of said fixed stop means and snaps into engagement with the other fixed stop means with change in tension in said pull wire, the curvatures of the intermediate and end parts of the vane change in magnitude but not in direction.

5. The combination according to claim 4, including a metal channel member having an opening in one wall thereof and provided with a mounting step adjacent one end of said wall, said fixed end of said plate being fixed to said step and the free end of said plate being alined with said opening, a fiat conductor insulatedly mounted within said channel member and extending from beyond one end thereof to said opening and being shaped at the inner end thereof to serve as one of said fixed stop members, the other of said stop members comprising a hook-shaped member having a part extending over the free end of said plate and a shank portion extending into said opening and mounted on the inner end of said fiat conductor, a second flat conductor insulatedlymounted within said channel member and extending from the other end thereof to a location short of said opening, said last mentioned flat conductor having a part bent out from the outer end thereof to serve as anchorage for said pull wire, and means on the free end of said plate for electrically insulating the plate from one of said stop members.

6. The combination according to claim wherein the inner end of said first mentioned conductor member has a part extending outwardly from the channel member for conjoint adjustment of said stop members relative to the free end of the plate member, and wherein said hook shaped member is bendable for adjustment of the spacing between said stop members.

7. The combination according to claim 4, wherein said plate is generally rectangular in shape, and said slots are non-parallel to define a vane decreasing in width in the direction from the fixed to the free end of the plate.

8. The combination according to claim 4 including a base member of insulating material carrying terminal connectors on one side thereof, a frame member mounted at one end on the other side of said base member and electrically connected to one of said terminal connectors, said frame having a shoulder on the unmounted end providing a mounting surface for the fixed end of said plate spaced from the rest of the frame, the fixed end of the frame having an apertured tongue pressed outwardly therefrom, said pull wire being insulatedly anchored in the aperture in said tongue, and means for mounting said fixed stop members on said base in electrical connection with other of said terminal connectors.

9. A wire controlled snap switch comprising in combination a plate member having slots therein defining a central strip, said strip, in the absence of external force, bowing outwardly from the plane of the plate member, said plate member being fixedly mounted at one end only, fixed stop means, including at least one electrical contact, positioned at opposite sides of the free end of said plate member, a pull wire extending generally parallel to said plate member, means for anchoring one end of said wire to the ,convex side of the end of said central strip adjacent the fixed end of the plate member, means anchoring said wire at another point thereof under a tension sufiicient to cause an intermediate part of said strip to assume a curvature opposite to the curvatures of the ends thereof with the free end of said plate member engaging one of said stop means and means for changing the tension in said pull wire to cause the free end of said plate member to snap into engagement with the other of said stop means with variations in amplitude of the depth of curvatures of the intermediate and end parts of said strip.

10. The combination according to claim 3, including a metal channel member having an opening in one wall thereof and provided with a mounting step adjacent one end of said wall, said fixed end of said plate being fixed to said step and the free end of said plate being alined with said opening, a flat conductor insulatedly mounted within said channel member and extending from beyond one end thereof to said opening and being shaped at the inner end thereof to serve as one of said fixed stop members, the other of said stop members comprising a hookshaped member having a part extending over the free end of said plate and a shank portion extending into said opening and mounted on the inner end of said fiat conductor, a second flat conductor insulatedly mounted within said channel member and extending from the other end thereof to a location short of said opening, said last mentioned flat conductor having a part bent out from the outer end thereof to serve as anchorage for said expansible wire, and means on the free end of said plate for electrically insulating the plate from one of said stop members.

11. The combination according to claim 10 wherein the inner end of said first mentioned conductor member has a part extending outwardly from the channel member for conjoint adjustment of said stop members relative to the free end of the plate member, and wherein said hook shaped member is bendable for adjustment of the spacing between said stop members.

12. The combination according to claim 3 including a base member of insulating material carrying terminal connectors on one side thereof, a frame member mounted at one end on the other side of said base member and electrically connected to one of said terminal connectors, said frame having a shoulder on the unmounted end providing a mounting surface for the fixed end of said plate spaced from the rest of the frame, the fixed end of the frame having an apertured tongue pressed outwardly therefrom, said expansible wire being insulatedly anchored in the aperture in said tongue, and means for mounting said fixed stop members on said base in electrical connection with other of said terminal connectors.

References Cited in the file of this patent UNITED STATES PATENTS 1,868,500 Hanel July 26, 1932 2,225,086 Schramm Dec. 17, 1940 2,299,767 Schmidinger Oct. 27, 1942 2,388,712 Schmidinger Nov. 13, 1945 2,537,485 Sitzer et a1. Jan. 9, 1951 2,644,899 Perry July 7, 1953 2,700,083 Harmon Jan. 18, 1955 FOREIGN PATENTS 117,171 Sweden Sept. 10, 1946 

